Today in spite of the fact that resources (like CPU power and disk space) are cheaper than before, increasing e-mail usage and the unpredictability associated with its size and volume can be very costly to individuals and corporations alike. E-mail is now a very commonly used way of sending and receiving information. E-mail may be sent between users on a local area network or a wide area network across the Internet for example. E-mail usage continues to increase, and it is not uncommon for an e-mail user to receive many hundreds of messages in a day. Many of these messages may themselves have lengthy attachments, which need a great deal of storage space, such as graphics files. In addition, there is growth in volume of spam e-mail which is unsolicited (predominantly unwanted) e-mail, and which also serves to fill up an e-mailbox. When an e-mailbox runs out of user space to store incoming e-mail, existing e-mail systems simply then bounce the e-mail back to the sender indicating that this e-mail was not delivered. Ordinarily, the receiver is not notified that an e-mail delivery failed. Thus, an important e-mail could be missed, and the receiver does not know this. This could have potentially disastrous consequences in business for example. In cases where the e-mail sent is large in size (perhaps due to attachments) the e-mail software does not deliver e-mail if the user space available is less than the e-mail size even if the amount of user space available is substantial.